<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
<style type="text/css">
	div{
		width: 200px;
		height: 100px;
		
		
		/*边框:粗细 样式 颜色  */
	 	border: 10px solid red;
	
	/*   单个方向  添加边框
	   
		border-left:10px solid red;
		border-right: 10px solid yellow;
		border-bottom: 10px solid blue;
		border-top: 10px solid green; */
		
		/*圆角  值越大越圆   当值为宽高一半时变圆(前提是宽高一样)*/
		border-radius: 54px;
		background-color: green;
	}
/*行内元素边框不影响元素所占高度  */	
		#s1{
			border: 10px solid blue;
		}


</style>
</head>
<body>
	<div></div>
	<span id="s1">这是个行级元素 span1</span>   	<span>这是个行级元素 span2</span>
	<div> </div>
</body>
</html>